K+ channel openers suppress myotonic activity of human skeletal muscle in vitro.
Isolated fibre bundles from myotonic human skeletal muscle showed after-contractions and spontaneous mechanical activity. The K+ channel openers cromakalim (10-100 mumols/l) and EMD 52962 (1-10 mumols/l) completely suppressed these abnormalities in mechanical activity. Voltage-clamp experiments revealed that cromakalim (100 mumols/l) increased the membrane K+ conductance of isolated, non-myotonic human skeletal muscle fibres 4-fold; Cl- conductance was not altered. The data show that myotonia is suppressed by an increase in in membrane K+ conductance.
Quasthoff
S
S
Physiologisches Institut, Universität München, F.R.G.
Spuler
A
A
Spittelmeister
W
W
Lehmann-Horn
F
F
Grafe
P
P
D001578:Benzopyrans / Q000494:pharmacology; D002463:Cell Membrane Permeability / Q000187:drug effects; D019806:Cromakalim; D004095:Dihydropyridines / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D008839:Microelectrodes; D009119:Muscle Contraction / Q000187:drug effects; D009132:Muscles / Q000187:drug effects / Q000378:metabolism*; D015221:Potassium Channels / Q000187:drug effects*; D011758:Pyrroles / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology
D001578:Benzopyrans; D004095:Dihydropyridines; D015221:Potassium Channels; D011758:Pyrroles; D014665:Vasodilator Agents; D019806:Cromakalim; C061050:bimakalim